1. Field of the Invention
The present invention relates to a portable drilling machine, and more particularly to a portable drilling machine adapted to be carried by an operator to perform drilling operation.
2. Description of the Prior Art
As generally known in the art, portable drilling machines are used to drill holes in walls when, for example, anchors need to be installed at a construction site related to electricity, facility, or hardware. Korean Patent Application No. 2000-11714 (entitled “Multi-functional dust collection device for drill”) discloses a portable drilling machine having a means for collecting dust, which is created during drilling operation.
FIG. 18 is an exploded perspective view of a conventional portable drilling machine, and FIG. 19 is an assembled perspective view thereof.
A conventional portable drilling machine, as shown in the drawings, includes a drill 110, a dust collector 120 coupled to the front end of the drill 110, and a drilling depth regulator 140 coupled to the upper end of the dust collector 120.
The drill 110 includes a housing 111 having a neck 111a formed on its front surface, a drill chuck 112 coupled to the front end of the neck 111a, a drill bit 113 detachably coupled to the drill chuck 112, and a driver (not shown) placed inside the housing 111.
The driver (not shown) provides either the drill bit 113 or the drill chuck 112 with a rotational driving force in response to switch operation from the operator.
The dust collector 120 has a corrugated tube 122 detachably coupled to the neck 111a by a clamp 121.
The corrugated tube 122 is adapted to extend and retract.
The drilling depth regulator 140 includes a retaining tube 141 coupled to the upper side of the clamp 121, a guide tube 142 fixedly inserted into the retaining tube 141, and an actuating rod 143 inserted into the guide tube 142 while being able to slide.
The front end of the actuating rod 143 is retained by a bracket 144, which is positioned on the upper surface of the front end of the corrugated tube 122.
The conventional portable drilling machine, constructed as above, is operated as follow: the front end of the corrugated tube 112 is pressed against a to-be-drilled surface so that it is kept in contact with the surface. Then, the drill bit 113 or the drill chuck 112 is rotated to perform drilling operation.
Dust created during the drilling operation is directed to the interior of the corrugated tube 122 for collection.
When the drilling operation is over, the corrugated tube 122 is separate to remove the collected dust.
However, the conventional portable drilling machine has a problem in that, when the corrugated tube 122 extends/retracts with a slant relative to the longitudinal direction of the drill bit 113 during drilling operation, the corrugated tube 122 may interfere with the rotational motion of the drill bit 113 (i.e. drilling operation) by making contact with it.
In addition, the inner diameter of the corrugated tube 122 depends on the diameter of the neck 111a, because the corrugated tube 122 is coupled to the neck 111a by the clamp 121. This means that dust collection space is limited.